Rotary drag valve

ABSTRACT

A valve assembly comprising a rotary closure element which defines an axis of rotation and is selectively movable between a fully open position and a fully closed position. Mounted to and movable with the rotary closure element is an impedance assembly. The impedance assembly defines an inflow end and an outflow end, and comprises a plurality of fluid passageways which extend from the inflow end to the outflow end. Also partially defined by the impedance assembly is a flow opening which extends from the inflow end to the outflow end. The fluid passageways and the flow opening are oriented relative to each other such that a portion of a flow through the valve assembly is directed into the fluid passageways and a portion of the flow is directed through the flow opening when the closure element is in the fully open position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. applicationSer. No. 10/122,276 entitled DRAG BALL VALVE filed Apr. 12, 2002.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

(Not Applicable)

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to rotary valves, and moreparticularly to an energy attenuating ball valve which includes animpedance assembly mounted within and movable with the closure elementor “ball” of the ball valve.

2. Discussion of Background

There is currently known in the prior art linear valve assemblies whichare outfitted to include a noise attenuation or impedance assembly. Suchvalves are often referred to in the relevant industry as “drag valves”.Linear valves as currently known in the prior art typically include anannular impedance assembly which includes a plurality of annular diskswhich each define a plurality of radially extending, tortuous flowpassages and are secured to each other in a stacked arrangement.Disposed within the interior of the impedance assembly is a piston whichis cooperatively engaged to an actuator operative to facilitate thereciprocal movement of the piston within the impedance assembly. Whenthe piston is in a lowermost position, none of the passages of theimpedance assembly are exposed to an incoming flow. As the piston ismoved upwardly toward an open position, flow passes through the passagesof the impedance assembly to provide an exit flow through the linearvalve. The amount of flow through the impedance assembly is varied bythe position of the piston, which in turn varies the area or proportionof the impedance assembly exposed to the incoming flow within theinterior thereof.

Though the above-described linear valve arrangement provides significantnoise reduction capabilities, in certain applications it is oftendesirable to employ the use of a rotary valve utilizing a rotary closureelement as an alternative to a linear valve. Since currently knownlinear impedance valves are typically considered to provide superiornoise reduction capabilities as compared to rotary valves, the presentinvention addresses this disparity by providing a rotary valvearrangement which retains the benefits o the impedance assemblyassociated with linear valves, while still employing the use of a rotaryclosure element. As will be discussed in more detail below, in thepresent invention, the impedance assembly is carried by the rotaryclosure element of the rotary or ball valve which may be adapted for usein large, high capacity applications for which an equivalent linearvalve would be excessively expensive (attributable to manufacturingobstacles) and potentially susceptible to instability problems. These,and other advantages of the present invention, will be discussed in moredetail below.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a valveassembly comprising a rotary closure element defining an axis ofrotation and selectively movable between a fully open position and afully closed position. Mounted to and movable within the rotary closureelement is an impedance assembly. The impedance assembly defines aninflow end and an outflow end, and comprises a plurality of fluidpassageways which extend from the inflow end to the outflow end. Theimpedance assembly also partially defines a flow opening which extendsthrough at least a portion of the bore of the rotary closure elementinto which the impedance assembly is mounted. The fluid passageways andsuch flow opening are oriented relative to each other such that aportion of flow through the valve assembly is directed into the fluidpassageways, with a portion of the flow being directed through the flowopening when the closure element is in its fully open position.

The fluid passageways may be disposed, in their entirety, downstream ofthe axis of rotation of the closure element when the same is in itsfully open position. Alternatively, the impendence assembly may beformed such that certain ones of the fluid passageways are disposed intheir entirety downstream of the axis of rotation of the closure elementwhen the same is in its fully open position, with certain ones of thefluid passageways including portions or segments which extend upstreamand downstream of the axis of rotation when the closure element is inits fully open position. The fluid passageways may each be tortuous,defining a series of turns which extend at generally right anglesrelative to each other, with such tortuous fluid passageways definingdiffering numbers of turns.

The impedance assembly is interfaced to the rotary closure element suchthat flow through the valve assembly is applied initially to the fluidpassageways having a greater number of turns when the closure element ismoved from its fully closed position toward its fully open position.

The impedance assembly comprises a series of plates which are secured toeach other in a stacked arrangement. Each of the plates includes aplurality of flow passages (e.g., slots, openings, etc.) formed thereinwhich collectively define the fluid passageways when the plates arestacked upon each other. The plates are stacked so as to extend along anaxis which is generally perpendicular or normal to the axis of the bore(i.e., extends in generally parallel relation to the axis of rotation ofthe closure element). The surfaces of the plates collectively definingthe inflow end of the impedance assembly are preferably beveled so as toextend at an acute angle relative to the axis of the bore. The surfacesof the plates collectively defining the outflow end of the impedanceassembly are preferably arcuately contoured so as to extend insubstantially flush or continuous relation to the outer surface of thegenerally spherical closure element. The impedance assembly may furthercomprise a layer of wire mesh material which is attached to and coversthe inflow end thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings wherein:

FIG. 1 is a cross-sectional view of an exemplary rotary valve having aclosure element including an impedance assembly constructed inaccordance with a first embodiment of the present invention;

FIG. 2 is a front perspective view of the closure element and impedanceassembly of the first embodiment shown in FIG. 1;

FIG. 3 is a front elevational view of the closure element and impedanceassembly shown in FIG. 2;

FIG. 4 is a cross-sectional view of the closure element and impedanceassembly shown in FIGS. 2 and 3;

FIG. 5 is a front perspective view of the impedance assembly of thefirst embodiment;

FIG. 6 is a cutaway view of the impedance assembly of the firstembodiment illustrating the tortuous flow passageways defined thereby;

FIG. 7 is a cross-sectional view of the impedance assembly of the firstembodiment;

FIG. 8 is an exploded view of the impedance assembly of the firstembodiment;

FIG. 9 is a front perspective view of a closure element including animpedance assembly constructed in accordance with a second embodiment ofthe present invention;

FIG. 10 is a front elevational view of the closure element and impedanceassembly shown in FIG. 9;

FIG. 11 is a front perspective view of the impedance assembly of thesecond embodiment;

FIG. 12 is a front elevational view of the impedance assembly of thesecond embodiment;

FIG. 13 is a side-elevational view of the impedance assembly of thesecond embodiment;

FIG. 14 is a cross-sectional view of the impedance assembly of thesecond embodiment;

FIG. 15 is a front perspective view of a closure element including animpedance assembly constructed in accordance with a third embodiment ofthe present invention;

FIG. 16 is a rear elevational view of the closure element and impedanceassembly shown in FIG. 15;

FIG. 17 is a front perspective view of the impedance assembly of thethird embodiment;

FIG. 18 is a front elevational view of the impedance assembly of thethird embodiment;

FIG. 19 is a cut-away perspective view of the impedance assembly of thethird embodiment illustrating the internal configuration of one of theflow openings thereof;

FIG. 20 is an exploded view of the impedance assembly of the thirdembodiment in a pre-machined configuration;

FIG. 21 is a rear perspective view of the impedance assembly of thethird embodiment in a partially machined configuration;

FIG. 22 is a cross-sectional view taken along line 22—22 of FIG. 21;

FIG. 23 is an exploded view of one of the disk assemblies of theimpedance assembly of the third embodiment in a pre-machinedconfiguration;

FIG. 24 is a cross-sectional view taken from a front perspective of anexemplary rotary valve having a closure element including an impedanceassembly constructed in accordance with a fourth embodiment of thepresent invention;

FIG. 25 is a cross-sectional view taken from a rear perspective of therotary valve shown in FIG. 24 illustrating the impedance assembly of thefourth embodiment;

FIG. 26 is a cross-sectional view taken from a top perspective of anexemplary rotary valve including the impedance assembly of the fourthembodiment, illustrating the closure element of the rotary valve in apartially open state;

FIG. 27 is a front elevational view of the closure element and impedanceassembly of the fourth embodiment;

FIG. 28 is a rear elevational view of the impedance assembly of thefourth embodiment;

FIG. 29 is a cross-sectional view of the closure element taken from arear perspective, illustrating the impedance assembly of the fourthembodiment as mounted within the bore of the closure element;

FIG. 30 is an exploded view of the impedance assembly of the fourthembodiment in a pre-machined configuration;

FIG. 31 is a rear perspective view of the impedance assembly of thefourth embodiment in a pre-machined configuration;

FIG. 32 is an exploded view of one of the disk assemblies of theimpedance assembly of the fourth embodiment in a pre-machinedconfiguration; and

FIG. 33 is an exploded view similar to FIG. 32, illustrating one of thedisk assemblies of the impedance assembly of the fourth embodiment in apost-machined configuration.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein the showings are for purposes ofillustrating preferred embodiments of the present invention only, andnot for purposes of limiting the same, FIG. 1 provides a cross-sectionalview of a rotary valve 10 (e.g., a ball valve) having a rotary closureelement 12 (e.g., a ball) outfitted to include an on-board impedanceassembly 14 constructed in accordance with a first embodiment of thepresent invention. The valve 10 includes a housing 16 which defines aflow path 18 extending axially therethrough. The closure element 12 isoperatively positioned within the flow path 18 of the housing 16, andeffectively segregates the flow path 18 into an inflow section 20 and anoutflow section 22. As best seen in FIG. 4, the closure element 12defines a bore 24 which extends axially therethrough. The formation ofthe bore 24 within the closure element 12 truncates opposed ends of theclosure element 12 which otherwise has a generally spherical shape. Inthis regard, the bore 24 includes an inflow end 26 and an outflow end 28which are each defined by the closure element 12.

As further seen in FIG. 4, attached to the closure element 12 is a stem30. The stem 30 extends radially from the closure element 12 insubstantially perpendicular relation to the axis of the bore 24. In thevalve 10, the closure element 12 is oriented within the flow path 18such that the axis of the bore 24 is selectively placeable into coaxialalignment with the axis of the flow path 18, with the axis of the stem30 extending in generally perpendicular relation to the axis of the flowpath 18. In this regard, the actuation of the closure element 12 to afully open position causes fluid flowing through the inflow section 20of the flow path 18 to flow into the inflow end 26 of the bore 24 alongthe axis thereof and subsequently into the outflow section 22 of theflow path 18 via the outflow end 28 of the bore 24. When actuated to itsfully closed position, the closure element 12 is rotated such that theaxis of the bore 24 extends in generally perpendicular relation to theaxis of the flow path 18, thus blocking the flow of fluid through theflow path 18 due to the impingement of the fluid flowing through theinflow section 20 against a side of the closure element 12.

As will be recognized, the closure element 12 may be rotated to variousdegrees of an open position between its fully open position and itsfully closed position, i.e., the axis of the bore 24 may extend at anangle of between zero degrees and ninety degrees relative to the axis ofthe flow path 18. In FIG. 1, the closure element 12 is shown as beingrotated into an orientation wherein the axis of the bore 24 extends atan angle of approximately forty-five degrees relative to the axis of theflow path 18, thus placing the valve 10 into a partially open state.Those of ordinary skill in the art will recognize that the structuralattributes of the valve 10 are exemplary only, and that the impedanceassembly 14 of the first embodiment of the present invention as will bedescribed in more detail below may be employed in a multiplicity ofdifferently configured rotary valves.

Referring now to FIGS. 2-8, there is shown the impedance assembly 14which is constructed in accordance with the first embodiment of thepresent invention. As indicated above, the impedance assembly 14 iscarried by the closure element 12, and more particularly is operativelypositioned within the bore 24 in a manner which will be described inmore detail below. As will also be discussed below, the structuralattributes of the impedance assembly 14 allow the same to be retrofittedto the closure element 12 of an existing valve 10, or provided as anoriginal component thereof.

The impedance assembly 14 comprises a cylindrically configured mainfeeder cap 32 which, in a preliminary, un-machined states, defines agenerally planar outer surface 34 and an opposed, generally planar innersurface. Disposed within the main feeder cap 32 are a plurality of mainfeeder passages 36 which extend therethrough. The main feeder passages36 are segregated into various sets, with one set of the main feederpassages 36 having elongate, slot-like configurations and being arrangedin an arcuate pattern, and other sets of the main feeder passages 38each having generally circular configurations. As seen in FIGS. 2 and 3,two sets of the circularly configured main feeder passages 36 aredisposed at respective ones of the opposed ends of the arcuate set ofelongate main feeder passages 36. Also disposed within the main feedercap 32 is an enlarged opening 37.

As best seen in FIGS. 7 and 8, in addition to the main feeder cap 32,the impedance assembly 14 includes a secondary feeder cap 38 which has acircular, plate-like configuration and is abutted against the innersurface of the main feeder cap 32. Disposed within the feeder cap 38 area plurality of feeder cap passages 40 and an opening 41 which has thesame general profile or shape as the opening 37 of the main feeder cap32. The impedance assembly 14 further comprises a plurality ofcircularly configured expansion plates 42, each of which includes aplurality of expansion passages 44 formed therein. In addition to theexpansion passages 44, each expansion plate 42 includes an opening 45disposed therein which has the same general shape or profile as theabove-described openings 37, 41. Also included in the impedance assembly14 are a plurality of circularly configured spacer plates 46 which areinterleaved between respective pairs of the expansion plates 42 and eachinclude a plurality of spacer passages 48 therein. In addition to thespacer passages 48, each expansion plate 42 includes an opening 49disposed therein which has the same general shape or profile as theopenings 37, 41, 45. Finally, the impedance assembly 14 includes acircularly configured exit plate 50 which itself includes a plurality ofexit passages 52 disposed therein. The exit plate 50 also includes anopening 53 disposed therein which has the same general shape or profileas the openings 37, 41, 45, 49.

In the impedance assembly 14, the main feeder cap 32, feeder cap 38, andexpansion, spacer and exit plates 42, 46, 50 are assembled in a stackedarrangement, and are preferably of equal outer diameters. As indicatedabove, the feeder cap 38 is abutted against the inner surface of themain feeder cap 36, with the expansion and spacer plates 42, 46 beingstacked in succession upon the feeder cap 38. The uppermost expansionplate 42 is abutted against that surface of the feeder cap 38 oppositethat abutted against the inner surface of the main feeder cap 32. Theexit plate 50 is abutted against the lowermost expansion plate 42. Themain feeder cap 32, feeder cap 38, and expansion, spacer and exit plates42, 46, 50 are preferably maintained in a stacked arrangement via brazedconnections, though other attachment methods may be employed as analternative.

When the impedance assembly 14 is initially assembled, the main feedercap 32, feeder cap 38, and expansion, spacer and exit plates 42, 46, 50are stacked upon each other such that the main feeder passages 36,feeder cap passages 40, expansion passages 44, spacer passages 48, andexit passages 52 are oriented relative to each other in a mannercollectively defining a plurality of tortuous passageways 54 and aplurality of generally straight passageways 56 which each extend throughthe impedance assembly 14. Similar to the main feeder passages 36, thefeeder cap passages 40 of the feeder cap 48 include those which have anelongate, slot-like configuration and are arranged in arcuate patterns,and those which have a generally circular configuration. The expansionpassages 44 of each of the expansion plates 42, the spacer passages 48of each of the spacer plates 46, and the exit passages 52 of the exitplate 50 are also provided in both elongate and circular configurations.

In the impedance assembly 14, the main feeder cap 32, feeder cap 38, andexpansion, spacer and exit plates 42, 46, 50 are stacked upon each othersuch that the circularly configured passages thereof are disposed incoaxially aligned sets. Each coaxially aligned set of circularlyconfigured passages collectively define a respective one of the straightpassageways 56 of the impedance assembly 14. The elongate passages ofthe main feeder cap 32, feeder cap 38, and expansion, spacer and exitplates 42, 46, 50 are also arranged in sets wherein the passages of eachset are only partially aligned with each other (i.e., only partiallyoverlap) such that each set of the partially aligned elongate passagescollectively define a respective one of the tortuous passageways 54.

As seen in FIG. 6, the tortuous passageways 54 of the impedance assembly14 are not formed to provide uniform noise or energy attenuationcharacteristics. In this regard, those tortuous passageways 54 partiallydefined by the main feeder passages 36 disposed in the approximatecenter of the arcuate arrangement thereof provide the highest level ofenergy attenuation capability (i.e., define the greatest number ofturns). The noise or energy attenuating capabilities of the remainingtortuous passageways 54 progressively decrease (i.e., the number ofturns defined by the passageways 54 is reduced) as they approachrespective ones of the opposed ends of the arcuate arrangement of mainfeeder passages 36. As such, those tortuous passageways 54 disposedclosest to each of the sets of circular main feeder passages 36 at theopposed ends of the elongate main feeder passages 36 define the leastnumber of turns, and hence provide a level of energy attenuationexceeding only that of the straight passageways 56.

As is further seen in FIG. 8, when the impedance assembly 14 isinitially assembled, the openings 37, 41, 45, 49 and 53 are also alignedwith each other and collectively define a flow opening 58 which extendsthrough the impedance assembly 14. The remaining portions of the mainfeeder cap 32, feeder cap 38, and expansion, spacer and exit plates 42,46, 50 collectively define an annular outer wall of the impedanceassembly 14 and a circumferential section which spans in the range offrom about ninety degrees to about one hundred twenty degrees andincludes each of the tortuous passageways 54 and straight passageways 56extending therethrough. As such, the flow opening 58 collectivelydefined by the openings 37, 41, 45, 49, 53 spans in the range from about240 degrees to about 270 degrees. Prior to the assembly of the impedanceassembly 14, the outer surface 34 of the main feeder cap 32 is machinedso as to provide the same with an arcuate, generally convexconfiguration. The pre-machining thickness of the main feeder cap 32allows for the completion of this machining operation.

Referring now to FIGS. 2-4, upon the fabrication of the impedanceassembly 14, the same is advanced into the bore 24 of the closureassembly 12. It is contemplated that the impedance assembly 14 may be“shrink-fit” into the closure element 12. However, those of ordinaryskill in the art will recognize that alternative attachment methods maybe employed to facilitate the interface of the impedance assembly 14 tothe closure element 12. In any such attachment method, it is preferredthat the inner surface of the closure element 12 defining the bore 24thereof be formed to include an annular shoulder 60 which serves as anabutment or stop surface for the impedance assembly 14. In this regard,the shoulder 60 is oriented such that the abutment of the exit plate 50thereagainst causes the arcuate outer surface 34 of the main feeder cap32 to extend in a flush or continuous relationship with the outersurface of the closure element 12 at the inflow end 26 of the bore 24.In this regard, it is contemplated that the outer surface 34 of the mainfeeder cap 32 will be machined such that the contour is complementary tothat of the outer surface of the closure element 12.

Due to the configuration of the impedance assembly 14, the number oftortuous and straight passageways 54, 56 exposed to flow along the axisof the flow path 18 varies as the closure element 12 is rotated from itsfully closed position toward its fully open position. In this regard,when the closure element 12 is initially cracked open, fluid will flowonly into those tortuous passageways 54 imparting the highest level ofenergy attenuation, i.e., only those tortuous passageways 54 partiallydefined by the main feeder passages 36 disposed in the approximatecenter of the arcuate arrangement thereof are exposed to the fluid flow.As the opening of the closure element 12 progresses, the remainingtortuous passageways 54 of lesser energy attenuating capability areprogressively exposed to the fluid flow. Thus, the number of tortuouspassageways 54 exposed to fluid flow progressively increases as theclosure element 12 is rotated toward its fully open position. Due totheir orientations relative to the tortuous passageways 54, the straightpassageways 56 are exposed to fluid flow once flow has commenced throughvirtually all of the tortuous passageways 54. The continued rotation ofthe closure element 12 toward its fully open position then allows fluidto flow through the flow opening 58 defined by the impedance assembly 14in an unrestricted manner. When the closure element 12 is ultimatelyrotated to its fully open position, a portion of the fluid flowcontinues to flow through the tortuous and straight passageways 54, 56,with the majority of the fluid flow passing through the flow opening 58.Thus, the impedance assembly 14 provides the benefits of those utilizedin linear valve arrangements, yet imparts those benefits to the rotaryclosure element 12 of the valve 10.

Referring now to FIGS. 9-14, there is shown an impedance assembly 62which is constructed in accordance with a second embodiment of thepresent invention. Like the impedance assembly 14 of the firstembodiment described above, the impedance assembly 62 is carried by theclosure element 12, and more particularly is operatively positionedwithin the bore 24 in a manner which will be described in more detailbelow. The structural attributes of the impedance assembly 62 also allowthe same to be retrofitted to the closure element 12 of an existingvalve 10, or provided as an original component thereof.

The impedance assembly 62 comprises a feeder cap 64 which is machined soas to define an arcuate, convex outer surface 66. Disposed within thefeeder cap 64 are a plurality of feeder passages 68 which extendtherethrough. Each of the feeder passages 68 has a generally rectangularcross-sectional configuration, though those of ordinary skill in the artwill recognize that the present invention is not intended to be limitedto any particular shape for the feeder passages 68. Also disposed withinthe feeder cap 64 is a generally crescent-shaped opening 70.

As best seen in FIG. 13, in addition to the feeder cap 64, the impedanceassembly 62 includes a plurality of circularly configured impedanceplates 72. The impedance plates 72 each include a plurality of impedancepassages formed therein. In addition to the impedance passages, each ofthe impedance plates 72 includes an opening formed therein which has thesame general shape or profile of the opening 70 formed within the feedercap 64. The impedance plates 72 are stacked upon each other, with anupper most one of the impedance plates 72 being abutted against theinner surface of the feeder cap 64. In addition to the feeder cap 64 andimpedance plates 72, the impedance assembly 62 includes a plurality ofexit passages disposed therein. In addition to the exit passages, theexit plate 74 includes an opening disposed therein which has the samegeneral shape or profile as the opening 70 of the feeder cap 64 and theopening within each of the impedance plates 72.

In the impedance assembly 62, the feeder cap 64, impedance plates 72 andexit plate 74 are assembled in a stacked arrangement, and are preferablyof equal outer diameters. As indicated above, the upper most impedanceplate 72 within the stack is abutted against the inner surface of thefeeder cap 64, with the impedance plates 72 being stacked in successionupon the feeder cap 64. The exit plate 74 is abutted against the lowermost impedance plate 72. The feeder cap 64, impedance plates 72 and exitplate 74 are preferably maintained in a stacked arrangement via brazedconnections, though other attachment methods may be employed as analternative.

When the impedance assembly 62 is initially assembled, the feeder cap 64and impedance and exit plates 72, 74 are stacked upon each other suchthat the feeder passages 68, impedance passages and exit passages areoriented relative to each other in a manner collectively defining aplurality of tortuous passageways 76 which are best shown in FIG. 14. Asis apparent from FIG. 14, some of the tortuous passageways 76 extendlongitudinally through the entire length of the impedance assembly 62(i.e., terminate at the exit plate 74), with some of the tortuouspassageways 76 terminating at a side surface collectively defined by theperipheral edges of the impedance plates 72. When the feeder cap 64 andimpedance and exit plates 72, 74 are stacked upon each other, the feederpassages 68, impedance passages, and exit passages are arranged in setswherein certain passages of each set are coaxially aligned with eachother in a longitudinal direction, with other passages of the same setbeing laterally or radially aligned with each other, or only partiallyaligned in a longitudinal or lateral direction (i.e., only partiallyoverlapping) such that each set of the passages collectively define arespective one of the tortuous passageways 76.

In addition to the feeder passages 68, impedance passages and exitpassages being aligned in sets to collectively define the tortuouspassageways 76, the opening 70 within the feeder cap 64 and openingswithin the impedance plates 72 and exit plate 74 are also aligned so asto collectively define a flow opening 78 which extends longitudinallythrough the impedance assembly 62. As is further seen in FIG. 14, thetortuous passageways 76 of the impedance assembly 62 are not formed toprovide uniform noise or energy attenuation characteristics. In thisregard, those tortuous passageways 76 disposed furthest from the flowopening 78 are configured to provide the highest level of energyattenuation capability (i.e., define the greatest number of turns). Thenoise or energy attenuating capabilities of the remaining tortuouspassageways 76 progressively decrease (i.e., the number of turns definedby the passageways 76 is reduced) as they approach the flow opening 78.Those tortuous passageways 76 having the highest energy attenuatingcapabilities (defining the greatest number of turns) each terminate atthe exit plate 74. Those tortuous passageways 76 of lesser energyattenuation capability terminate at the side surface collectively defineby the impedance plates 72, and hence facilitate outflow directly intothe flow opening 78.

Upon the fabrication of the impedance assembly 62, the same is advancedinto the bore 24 of the closure element 12. It is contemplated that theimpedance assembly 62 may be “shrink-fit” into the closure element 12.However, those of ordinary skill in the art will recognize thatalternative attachment methods may be employed to facilitate theinterface of the impedance assembly 62 to the closure element 12. Whenthe impedance assembly 62 is properly interfaced to the closure element12, the arcuate outer surface 66 of the feeder cap 64 will extend in aflush or continuous relationship with the outer surface of the closureelement 12 at the inflow end 26 of the bore 24. In this regard, it iscontemplated that the outer surface 66 of the feeder cap 64 will bemachined such that its contour is complimentary to that of the outersurface of the closure element 12.

Due to the configuration of the impedance assembly 62, the number oftortuous passageways 76 exposed to flow along the axis of the flow path18 varies as the closure element 12 is rotated from its fully closedposition toward its fully open position. In this regard, when theclosure element 12 is initially cracked open, fluid will flow only intothose tortuous passageways 76 imparting the highest level of energyattenuation. As the opening of the closure element 12 progresses, theremaining tortuous passageways 76 of lesser energy attenuatingcapability are progressively exposed to the fluid flow. Thus, the numberof tortuous passageways 76 exposed to fluid flow progressively increasesas the closure element 12 is rotated toward its fully open position. Thecontinued rotation of the closure element 12 toward its fully openposition then allows fluid to flow through the flow opening 78 definedby the impedance assembly 62 in an unrestricted manner. When the closureelement 12 is ultimately rotated to its fully open position, a portionof the fluid flow continues to flow through the tortuous passageways 76,with fluid flow also passing through the flow opening 78. Thus, like theimpedance assembly 14 described above, the impedance assembly 64 of thesecond embodiment provides the benefits of those utilized in linearvalve arrangements, yet imparts those benefits to the rotary closureelement 12 of the valve 10.

Referring now to FIGS. 15-23, there is shown an impedance assembly 80constructed in accordance with a third embodiment of the presentinvention. Like the impedance assemblies 14, 62 of the first and secondembodiments described above, the impedance assembly 80 of the thirdembodiment is carried by the closure element 12, and more particularlyis operatively positioned within the bore 24 in a manner which will bedescribed in more detail below. The structural attributes of theimpedance assembly 80 also allow the same to be retrofitted to theclosure element 12 of an existing valve 10, or provided as an originalcomponent thereof.

Referring now to FIGS. 20-22, the impedance assembly 80 comprises anupper cap 82 which, in a preliminary, un-machined state, has a generallyrectangular configuration defining an inlet side surface 82 a and anoutlet side surface 82 b. In this regard, the inlet and outlet sidesurfaces 82 a, 82 b are defined by respective ones of the longitudinalsides of the rectangularly configured upper cap 82. In addition to theupper cap 82, the impedance assembly 80 includes a plurality ofimpedance plate assemblies 84 which are maintained in a stackedarrangement, and are best shown in FIGS. 20 and 23. Each impedance plateassembly 84 comprises a rectangularly configured separator plate 86, arectangularly configured first impedance plate 88, and a rectangularlyconfigured second impedance plate 90. Formed within the first impedanceplate 88 are a plurality of elongate slots labeled 92 a-92 e,respectively. Also formed within the first impedance plate 88 adjacentthe inner ends of the slots 92 a-92 c are various openings 94, some ofwhich are formed within one of the longitudinal peripheral edge segmentsof the first impedance plate 88. Similarly, formed within the secondimpedance plate 90 are a plurality of openings 96, some of which alsoare formed within one of the longitudinal peripheral edge segments ofthe second impedance plate 90.

Within each impedance plate assembly 84, the separator plate 86, firstimpedance plate 88, and second impedance plate 90 are maintained in astacked arrangement. In this regard, the length and width dimensions ofthe separator plate 86, first impedance plate 88 and second impedanceplate 90 are preferably substantially equal, such that the longitudinaland lateral peripheral edge segments thereof are substantially flushwhen the plates 86, 88, 90 are stacked. The stacking is completed suchthat the openings 96 of the second impedance plate 90 partially overlapcorresponding openings 94 and slots 92 a-e of the first impedance plate88. The separator plate 86 is attached to one side or face of the secondimpedance plate 90 such that the second impedance plate 90 is disposedor sandwiched between the separator plate 86 and the first impedanceplate 88.

As is further seen in FIG. 20, within the impedance assembly 80, theimpedance plate assemblies 84 are stacked upon the upper cap 82. Theuppermost impedance plate assembly 84 of the impedance assembly 80 doesnot include the separator plate 86, with the second impedance plate 90thereof being abutted directly against the bottom surface of the uppercap 82. For each successively stacked impedance plate assembly 84, theseparator plate 86 of each such impedance plate assembly 84 is abuttedagainst the first impedance plate 88 of the impedance plate assembly 84immediately above it.

In addition to the upper cap 82 and impedance plate assemblies 84, theimpedance assembly 80 includes a lower cap 90 which, like the upper cap82, has a generally rectangular configuration in its preliminary,un-machined state, and defines an inlet side surface 98 a and an outletside surface 98 b. In the impedance assembly 80, the top surface of thelower cap 98 is abutted against the first impedance plate 88 of thelowermost impedance plate assembly 84. As seen in FIGS. 20-22, thelength and width dimensions of the upper and lower caps 82, 98 are alsosubstantially equal to those of the plates 86, 88, 90, with thelongitudinal and lateral sides of the upper and lower caps 82, 98 beingsubstantially flush with the longitudinal and lateral peripheral edgesegments of the plates 86, 88, 90, i.e., the inlet side surfaces 82 a,98 a and outlet side surfaces 82 b, 98 b are substantially flush orcontinuous with respective ones of the longitudinal peripheral edgesegments of the plates 86, 88, 90.

As is seen in FIGS. 20 and 23, the upper and lower caps 82, 98 andplates 86, 88, 90 each preferably include an alignment or registryaperture 100 disposed within a corner region thereof. The alignmentapertures 100 are included in prescribed corner regions of the upper andlower caps 82, 98 and plates 86, 88, 90, and are adapted to facilitate aproper registry between such components in the stacking thereof. In thisregard, the apertures 100 are brought into coaxial alignment with eachother, and are adapted to receive a retention pin which, when advancedthereinto, assists in maintaining the upper and lower caps 82, 98 andplates 86, 88, 90 in a proper, stacked registry.

In the impedance assembly 80, the stacking of the upper cap 82,impedance plate assemblies 84, and lower cap 98 occurs in a mannerwherein the slots 92 a-e terminate at the longitudinal peripheral edgesegment of the first impedance plate 88 which extends along the inletside surfaces 82 a, 98 a of the upper and lower caps 82, 98, and theopenings 94, 96 are disposed adjacent to or formed within thelongitudinal peripheral edge segments of the first and second impedanceplates 88, 90 which extend along the outlet side surfaces 82 b, 98 b ofthe upper and lower caps 82, 98. In FIGS. 20 and 21, the impedance plateassemblies 84 are viewed from the rear perspective, and are shown from afront perspective in FIG. 23. The exploded view from the frontperspective in FIG. 23 demonstrates that each impedance plate assembly84 defines a plurality of tortuous passageways which extend between thelongitudinal peripheral edge segments of the plates 86, 88, 90 in spacedrelation to each other.

Due to the arrangement of the openings 94, 96 within the first andsecond impedance plates 88, 90, the tortuous passageway partiallydefined by the slot 92 a includes a total of eight turns, with thetortuous passageway partially defined by the slot 92 b defining a totalof six turns, the tortuous passageway partially defined by the slot 92 cdefining a total of four turns, and the tortuous passageways partiallydefined by the slots 92 d, 92 e each defining a total of two turns.Thus, the number of turns defined by the tortuous passageways decreasesas the passageways progress from left to right viewed from the frontperspective shown in FIG. 23. Those of ordinary skill in the art willrecognize that the number of turns defined by the tortuous passagewaysas described above is exemplary only, and that slots and openings may beformed in the impedance plates 88, 90 as needed to effectuate theimplementation of differing numbers of turns. Moreover, as is seen inFIGS. 20 and 21, the distance separating the slots 92 a-e and openings94, 96 from each other and from the lateral peripheral edge segments ofrespective ones of the first and second impedance plates 88, 90 is notperfectly uniform within all of the impedance plate assemblies 84.Rather, these separation distances are varied as needed to arrange thetortuous passageways in sets wherein the tortuous passageways of eachset define equal numbers of turns but extend in a generally arcuatepattern.

In the impedance assembly 80 of the third embodiment, the impedanceplate assemblies 84 and upper and lower caps 82, 98 are preferablymaintained in their stacked arrangement via brazed connections, thoughother attachment methods may be employed as an alternative. Upon thestacking of the upper and lower caps 82, 98 and impedance plateassemblies 84 in the above-described manner, a top flow opening 102 isformed into the upper cap 82 and extends between the inlet and outletside surfaces 82 a, 82 b thereof. Similarly, a bottom flow opening 104is formed into the lower cap 98 and extends between the inlet and outletside surfaces 98 a, 98 b thereof. The top and bottom flow openings 102,104 may each be formed within respective ones of the upper and lowercaps 82, 98 via a wire EDM process. As seen in FIG. 19, preferablydisposed within the top flow opening 102 is a first plate 106 and asecond plate 108 which are each attached (e.g., welded) to the upper cap82. The first plate 106 and second plate 108 are arranged within the topflow opening 102 relative to each other such that the top flow opening102 does not define a straight flow path, but rather defines a tortuousflow path defining two turns. Those of ordinary skill in the art willrecognize that differing numbers of plates may be disposed within thetop flow opening 102 in differing arrangements as needed to facilitatethe creation of differing numbers of turns, or that no plates at allneed be included within the top flow opening 102. In the impedanceassembly 80, the first and second plates 106, 108 are also disposedwithin the bottom flow opening 104 in the same arrangement shown in FIG.19A so as to define a tortuous passageway having two turns therein. Itwill further be recognized that the top and bottom flow openings 102,104 may each have a shape differing from that shown in the figures(e.g., tear drop, round, triangular, etc.) to give the trim a specificflow curve characteristic.

After the first and second plates 106, 108 have been inserted into eachof the top and bottom flow openings 102, 104, the upper and lower caps82, 98 and impedance plate assemblies 84 of the impedance assembly aremachined so as to impart to the stacked arrangement the generallyelliptical profile shown in FIGS. 17 and 18. As such, the impedanceassembly 80 includes an arcuate outer surface 110 collectively definedby portions of the upper and lower caps 82, 98 and impedance plateassemblies 84, and an arcuate inner surface 112 which is itselfcollectively defined by portions of the upper and lower caps 82, 98 andimpedance plate assemblies 84, and an arcuate inner surface 112 which isitself collectively defined by portions of the upper and lower caps 82,98 and impedance plate assemblies 84. The outer and inner surfaces 110,112 meet each other at a top apex 114 defined by the upper cap 82 anddisposed adjacent the top flow opening 102, and a bottom apex 116defined by the lower cap 98 and disposed adjacent the bottom flowopening 104. Within the machined impedance assembly 80, the tortuouspassageways of greatest noise or energy attenuating capability (i.e.,the tortuous passageways defining the greatest number of turns) aredisposed closest to the outer surface 110, with the number of turns (andhence the noise attenuating capability) of the tortuous passagewaysprogressively decreasing as they extend toward the inner surface 112.

Referring now to FIGS. 15 and 16, upon the impedance assembly 80 beingmachined in the above-described manner, the same is advanced into thebore 24 of the closure element 12. Such advancement is facilitated in amanner wherein the outer surface 110 of the impedance assembly 80directly engages or abuts a portion of the inner surface of the closureelement 12 which defines the bore 24 thereof. In this regard, it iscontemplated that the contour of the outer surface 110 will becomplementary to that of the inner surface of the closure element 12defining the bore 24, such that the outer surface 110 may be broughtinto direct, flush engagement therewith. When properly positioned withinthe bore 24, a portion of the impedance assembly 80 protrudes from theinflow end 26 of the bore 24. Additionally, the inner surface 112 of theimpedance assembly 80 and a portion of the inner surface of the closureelement 12 defining the bore 24 thereof collectively define a generallycrescent-shaped flow opening 118. The thickness of the impedanceassembly 80 is substantially less than the length of the bore 24. Thus,when the impedance assembly 80 is properly positioned within the bore24, the impedance assembly 80 extends to a depth which is substantiallyshort of the rotational axis of the closure element 12 (i.e., the axisof the stem 30). It is contemplated that the impedance assembly 80 willbe welded in place within the bore 24 of the closure element 12, thoughthose of ordinary skill in the art will recognize that alternativeattachment methods may also be employed.

Once the impedance assembly 80 has been properly secured within the bore24 of the closure element 12, that portion of the impedance assembly 80protruding from the inflow end 26 of the bore 24 is subjected to anothermachining operation which imparts an arcuate contour or profile theretoas needed to cause the exposed outer inflow end of the impedanceassembly 80 to be substantially flush or continuous with the outersurface of the closure element 12 at the inflow end 26 of the bore 24.Stated another way, the impedance assembly 80 is machined such that thecontour of the outer inflow end thereof is complementary to that of theouter surface of the closure element 12 as is best seen in FIG. 15.

Due to the configuration of the impedance assembly 80, the number oftortuous passageways exposed to flow along the axis of the flow path 18varies as the closure element 12 is rotated from its fully closedposition toward its fully open position. In this regard, when theclosure element 12 is initially cracked open, fluid will flow only intothose tortuous passageways of the impedance assembly 80 imparting thehighest level of noise or energy attenuation. As the opening of theclosure element 12 progresses, the remaining tortuous passageways of theimpedance assembly 80 of lesser noise or energy attenuating capabilityare progressively exposed to the fluid flow. Thus, the number oftortuous passageways exposed to fluid flow progressively increases asthe closure element 12 is rotated toward its fully open position.

In addition to flowing through the tortuous passageways, the fluid flowsinto the top and bottom flow openings 102, 104 of the impedance assembly80 which, as indicated above, are also tortuous. The continued rotationof the closure element 12 toward its fully open position then allowsfluid to flow through the flow opening 118 in an unrestricted manner.When the closure element 12 is ultimately rotated to its fully openposition, a portion of the fluid flow continues to flow through thetortuous passageways and top and bottom flow openings 102, 104 of theimpedance assembly concurrently with flow through the flow opening 118.Thus, like the impedance assemblies 14, 62 described above, theimpedance assembly 80 of the third embodiment provides the benefits ofthose utilized in linear valve arrangements, yet imparts those benefitsto the rotary closure element 12 of the valve 10.

One of the most significant structural distinctions between theimpedance assembly 80 of the third embodiment and the impedanceassemblies 14 and 62 of the first and second embodiments is that in theimpedance assembly 80 of the third embodiment, the impedance plateassemblies 84 are stacked in a direction which is generallyperpendicular or normal to the axis defined by the bore 24 of theclosure element 12. In contrast, the feeder caps and plates of theimpedance assemblies 14, 62 are stacked in a manner where they extendalong the axis defined by the bore 24 of the closure element 12.

Referring now to FIGS. 24-32, there is shown an impedance assembly 200constructed in accordance with a fourth embodiment of the presentinvention. The impedance assembly 200 of the fourth embodiment is alsocarried by the closure element 12 and, more particularly, is operativelypositioned within the bore 24 in a manner which will be described inmore detail below. The structural attributes of the impedance assembly200 also allow the same to be retrofitted to the closure element 12 ofan existing valve 10, or provided as an original component thereof.

The impedance assembly 200 comprises an upper cap 202 which, in apreliminary, un-machined state, has a generally rectangularconfiguration defining an inlet side surface 202 a and an outlet sidesurface 202 b. In addition to the upper cap 202, the impedance assembly200 includes a plurality of impedance plate assemblies 204 which aremaintained in a stacked arrangement, and are best shown in FIGS. 30-32.Each impedance plate assembly 204 comprises a separator plate 206, afirst impedance plate 208, and a second impedance plate 210. The plates206, 208, 210 each preferably have either a rectangular or squareconfiguration. Formed within the first impedance plate 208 are aplurality of openings 212. Similarly, formed within the second impedanceplate 210 are a plurality of openings 214. The openings 212, 214 are noteach of the same size, or arranged in the same patterns withinrespective ones of the first and second impedance plates 208, 210.Rather, the size and arrangement of the openings 212, 214 varies withincertain ones of the impedance plate assemblies 204 for reasons whichwill be discussed in more detail below.

Within each impedance plate assembly 204, the separator plate 206, firstimpedance plate 208, and second impedance plate 210 are maintained in astacked arrangement. In this regard, the length and width dimensions ofthe separator plate 206, first impedance plate 208 and second impedanceplate 210 are preferably substantially equal, such that correspondingperipheral edge segments thereof are substantially flush when the plates206, 208, 210 are stacked. The stacking is completed such that theopenings 214 of the second impedance plate 210 partially overlap one ormore corresponding openings 212 of the first impedance plate 208. Theseparator plate 206 is attached to one side or face of the firstimpedance plate 208 such that the first impedance plate 208 is disposedor sandwiched between the separator plate 206 and the second impedanceplate 210.

Within the impedance assembly 200, the impedance plate assemblies 204are stacked upon the upper cap 202. The second impedance plate 210 ofthe uppermost impedance plate assembly 204 is abutted directly againstthe bottom surface of the upper cap 202. For each successively stackedimpedance plate assembly 204, the second impedance plate 210 of eachsuch impedance plate assembly 204 is abutted against the separator plate206 of the impedance plate assembly 204 immediately above it. Thelowermost impedance plate assembly 204 within the stack does not includethe separator plate 206, as will be described in more detail below.

In addition to the upper cap 202 and impedance plate assemblies 204, theimpedance assembly 200 of the fourth embodiment includes a lower cap 216which, like the upper cap 202, has a generally rectangular or squareconfiguration in its preliminary, un-machined state, and defines aninlet side surface 216 a and an outlet side surface 216 b. In theimpedance assembly 200, the top surface of the lower cap 216 is abuttedagainst the first impedance plate 208 of the lowermost impedance plateassembly 204 which, as indicated above, does not include the separatorplate 206. The length and width dimensions of the upper and lower caps202, 216 are substantially equal to those of the plates 206, 208, 210such that the peripheral sides of the upper and lower caps 202, 216 aresubstantially flush with corresponding peripheral edge segments of theplates 206, 208, 210.

As is further seen in FIGS. 30-33, the upper and lower caps 202, 216 andplates 206, 208, 210 each preferably include one or more alignment orregistry apertures 218 disposed therein. The alignment apertures 218 areadapted to facilitate a proper registry between the upper and lower caps202, 216 and plates 206, 208, 210 in the stacking thereof. In thisregard, the apertures 218 are brought into coaxial alignment with eachother in a manner collectively defining two coaxially aligned sets, eachof which is adapted to receive a retention pin. The advancement of suchretention pins into the coaxially aligned sets of apertures 218 assistsin maintaining the upper and lower caps 202, 216 and plates 206, 208,210 in a proper stacked registry.

The impedance plate assemblies 84 as stacked between the upper cap 202and the lower cap 216 are shown in FIG. 31. As will be discussed in moredetail below, the impedance plate assemblies 204 and the upper and lowercaps 202, 216 are preferably maintained in their stacked arrangement viabrazed connections, though other attachment methods may be employed asan alternative. Subsequent to the stacking in the above-describedmanner, the upper and lower caps 202, 216 and intermediate impedanceplate assemblies 204 are preferably machined in a manner resulting inthe upper and lower caps 202, 216 and the impedance plate assemblies 204collectively defining an inflow side or end 220 of the impedanceassembly 200 which has an angled or beveled configuration, as best shownin FIG. 29. The inflow end 220 of the impedance assembly 200 ispreferably formed to extend at an angle of approximately forty-fivedegrees relative to the axis of the bore 24 of the closure element 12when the impedance assembly 200 is mounted therein.

In addition to being machined to define the beveled inflow end 220, theupper and lower caps 202, 216 and intervening impedance plate assemblies204 are further machined to collectively define an arcuately contoured,convex outflow side or end 222. The arcuate contour or profile of theoutflow end 222 is adapted to cause the same to be substantially flushor continuous with the outer surface of the closure element 12 at theoutflow end 28 of the bore 24 when the impedance assembly 200 is mountedtherein. Stated another way, the impedance assembly 200 is machined suchthat the contour of the outflow end 222 thereof is complementary to thatof the outer surface of the closure element 12. The machining operationwhich imparts the arcuate contour or profile to the outflow end 222 mayoccur prior or subsequent to the mounting of the impedance assembly 200into the bore 24 of the closure element 12. However, the machining ofthe upper and lower caps 202, 216 and impedance plate assemblies 204 asneeded to facilitate the formation of the beveled inflow end 220 willnecessarily occur prior to the mounting of the impedance assembly 200within the bore 24.

An exploded view of one of the impedance plate assemblies 204 of theimpedance assembly 200, subsequent to the completion of the machiningoperations used to facilitate the formation of the inflow and outflowends 220, 222, is shown in FIG. 33. As shown in FIG. 33, the machiningof the impedance plate assemblies 204 to form the beveled inflow end 220results in certain ones of the openings 212, 214 within the first andsecond impedance plates 208, 210 each communicating with or extending tothat edge segment of the corresponding plate 208, 210 which partiallydefines the inflow end 220. Similarly, the machining of the impedanceplate assemblies 204 to form the convex outflow end 222 results incertain ones of the openings 212, 214 extending to that peripheralsegment of the corresponding plate 208, 210 which partially defines theoutflow end 222. Certain ones of the openings 212, 214 of the first andsecond impedance plates 208, 210 are unaffected by the machiningoperations described above.

As is further seen in FIG. 33, as a result of the formation of theinflow and outflow ends 220, 222 in the above-described manner, each ofthe plates 206, 208, 210 defines an opposed pair of side peripheral edgesegments which extend between those peripheral edge segments definingrespective ones of the inflow and outflow ends 220, 222. The sideperipheral edge segments of each such pair are of differing lengths,with one being substantially shorter than the other. In addition tobeing machined to form the inflow and outflow ends 220, 222, the upperand lower caps 202, 216 and impedance plate assemblies 204 are furthermachined so as to impart to the stacked arrangement the generallyelliptical profile best shown in FIGS. 27-29. As such, the impedanceassembly 200 includes an arcuate outer surface 224 collectively definedby the side peripheral edge segments of the plates 206, 208, 210 ofshorter length and portions of the upper and lower caps 202, 216. Inaddition to the outer surface 224, the impedance assembly 200 defines anarcuate inner surface 226 which is collectively defined by the sideperipheral edge segments of the plates 206, 208, 210 of greater lengthand portions of the upper and lower caps 202, 216. These outer and innersurfaces 224, 226 meet each other at a top apex 228 defined by the uppercap 202, and a bottom apex 230 defined by the lower cap 216.

Due to the arrangement of the openings 212, 214 within the first andsecond impedance plates 208, 210 of each impedance plate assembly 204,each of the impedance plate assemblies 204 defines a plurality of fluidpassageways which are tortuous and extend between those peripheral edgesegments partially defining respective ones of the inflow and outflowends 220, 222. These tortuous fluid passageways are disposed in spacedrelation to each other and define differing numbers of right-angleturns. More particularly, the number of turns defined by the tortuousfluid passageways decreases as the passages progress from the outersurface 224 to the inner surface 226 as viewed from the frontperspective shown in FIG. 27. Thus, those passageways defining thegreatest number of turns are disposed closest to the side peripheraledge segments of the plates 208, 210 of greatest length, with thosepassageways defining the least number of turns being disposed closest tothe side peripheral edge segments of the plates 208, 210 of shorterlength. As is further seen in FIG. 33, the arrangement of the openings212, 214 within the plates 208, 210 maximizes the surface area on eachof the plates 208, 210 which is available for use as a brazing area.Such increased brazing area enhances the integrity of the attachmentbetween the plates 206, 208, 210 within the impedance assembly 200.

As will be recognized, those tortuous passageways providing the greatestnoise or energy attenuating capability are those defining the greatestnumber of turns which, as indicated above, are disposed closest to theouter surface 224. The number of turns (and hence the noise attenuatingcapability) of the tortuous passageways progressively decreases as theyextend toward the inner surface 226, as also indicated above.

Upon the impedance assembly 200 being machined in the above-describedmanner, the same is advanced into the bore 24 of the closure element 12.Such advancement is facilitated in a manner wherein the outer surface224 of the impedance assembly 200 directly engages or abuts a portion ofthe inner surface of the closure element 12 which defines the bore 24thereof. In this regard, it is contemplated that the contour of theouter surface 224 will be complementary to that of the inner surface ofthe closure element 12 defining the bore 24, such that the outer surface224 may be brought into direct, flush engagement therewith. Whenproperly positioned within the bore 24, the outflow end 222 of theimpedance assembly 200 will extend to the outflow end 28 of the bore 24in flush relation to the outer surface of the closure element 12.However, if the outflow end 222 has not yet been machined into theimpedance assembly 200, the same will be positioned within the bore 24such that a portion thereof protrudes from the outflow end 28 of thebore 24, with the impedance assembly 200 thereafter being machined so asto facilitate the formation of the outflow end 222 which extends incontinuous, flush relation to the outer surface of the closure element12.

The mounting of the impedance assembly 200 into the bore 24 of theclosure element 12 is preferably accomplished through the use of welds.Upon such mounting, the inner surface 226 of the impedance assembly 200and a portion of the inner surface of the closure element 12 definingthe bore 24 thereof collectively define a generally crescent-shaped flowopening 232. The thickness of the impedance assembly 200, even at itsthickest point, is substantially less than the length of the bore 24.Thus, when the impedance assembly 200 is properly positioned within thebore 24, the majority of the impedance assembly 200 (and hence themajority of the tortuous fluid passageways defined thereby) extendsbetween the rotational axis of the closure element 12 (i.e., the axis ofthe stem 30) and the outflow end 28 of the bore 24. However, as seen inFIG. 26, portions or segments of those fluid passageways defining thegreatest number of turns (i.e., those passageways disposed closest tothe outer surface 224) extend upstream of the rotational axis of theclosure element 12 (i.e., between the axis of the stem 30 and the inflowend 26 of the bore 24). However, those of ordinary skill in the art willrecognize that the impedance assembly 200 may be sized such that theentirety thereof is disposed downstream of the rotational axis of theclosure element 12.

Due to the configuration of the impedance assembly 200, the number oftortuous passageways directly impinged by flow along the axis of theflow path 18 varies as the closure element 12 is rotated from its fullyclosed position toward its fully open position. In this regard, as seenin FIG. 26, when the closure element 12 is initially cracked open, thefluid flow into the bore 24 directly impinges only those tortuouspassageways of the impedance assembly 200 imparting the highest level ofnoise or energy attenuation. As the opening of the closure element 12progresses, the remaining tortuous passageways of the impedance assembly200 of lesser noise or energy attenuating capability are progressivelydirectly impinged by the flow of fluid into the bore 24 of the closureelement 12. Thus, the number of tortuous passageways directly impingedby fluid flow into the bore 24 progressively increases as the closureelement 12 is rotated toward its fully open position. The continuedrotation of the closure element 12 toward its fully open position thenallows fluid to flow through the flow opening 232 in an unrestrictedmanner. When the closure element 12 is ultimately rotated to its fullyopen position, a portion of the fluid flow continues to flow through thetortuous passageways concurrently with flow through the flow opening232.

In the impedance assembly 200 of the fourth embodiment, the impedanceplate assemblies 204 are stacked in a direction which is generallyperpendicular or normal to the axis defined by the bore 24 of theclosure element 12. Advantageously, by orienting the inflow end 220 ofthe impedance assembly 200 downstream of the inflow end 26 of the bore24, any solid “trash” particles which become trapped in the inflow end220 of the impedance assembly 200 are downstream of the soft front seat234 of the valve 10. As a result, the susceptibility of the front seat234 to being cut or torn by such trash particles during rotation of theclosure element 12 between its fully open and fully closed positions iseliminated. As will be recognized, in typical valve construction, it ispreferred that the front seat 234 be fabricated from a soft material asis adapted to facilitate the creation of a bubble-tight seal (e.g., aClass 6 shut-off). As indicated above, the location of the impedanceassembly 200 at the back of the closure element 12 eliminates thesusceptibility to the tearing of the soft front seat 234 due to thesolid trash particles being collected inside the bore 24 of the closureelement 12, far away from the front seat 234. Thus, the soft upstreamfront seat 234 need not be used for throttling, and may be used only asa primary shut-off seal which is its main function in a regular trunnionball valve. As a result, the downstream back seat 236 may be convertedto a metal seal used strictly for throttling purposes.

In addition to the aforementioned advantages attributable to theplacement of the impedance assembly 200 to the back of the bore 24within the closure element 12, the formation of the angled inflow end220 of the impedance assembly 200 (which is located within the bore 24)provides an optimal angle for trash deflection. In this regard, solidparticles will tend to be deflected toward the flow opening 232, whichprovides a “self-flushing” feature. It is contemplated that theimpedance assembly 200 may be provided with a layer 238 of wire meshmaterial which is attached to and completely covers the inflow end 220(i.e., the deflection face). The wire mesh layer 238 covering the inflowend 220 further protects against any clogging of the tortuous fluidpassageways, while further enhancing the noise attenuation capabilitiesof the impedance assembly 200. It is contemplated that several layers238 of wire mesh material (as opposed to a single layer 238) may bestacked upon the inflow end 220. In this regard, the wire mesh layer(s)238, in addition to keeping trash out of the tortuous fluid passageways,can be used as a noise attenuation barrier, with differing levels ofnoise reduction being achievable based on the number of layers 238 ofwire mesh material stacked upon the inflow end 220. The increasedbrazing area on the plates 206, 208, 210, as described above, providesan increase in brazing quality and a reduced potential for any of theplates 206, 208, 210 from breaking off of the stack. Additionally, theoverall configuration of the impedance assembly 200 provides for the useof additional stringer welds to facilitate the attachment thereof to theclosure element 12.

Additional modifications and improvements of the present invention mayalso be apparent to those of ordinary skill in the art. For example, asshown in the accompanying figures, the impedance assembly 80 of thethird embodiment is formed to have a generally elliptical configuration,which results in the flow opening 118 being generally crescent-shapedwhen the impedance assembly 80 is advanced into the bore 24 of theclosure element 12. In this regard, the impedance assembly 80 may beformed to have alternative shapes as would cause the flow opening 118 tohave a shape other than a crescent shape. More particularly, the shapeof the flow opening 118 can be varied by modifying the shape of theimpedance assembly 80, with the shape of the flow opening 118 beingselected to provide a desired flow curve characteristic. The same holdstrue for the shape of the impedance assembly 200 and resultant shape ofthe flow opening 232. Additionally, it is contemplated that theimpedance assembly 200 may be sized and configured so as to completelycover or extend across the bore 24 of the closure element 12, i.e., theflow opening 232 is not defined. Thus, the particular combination ofparts described and illustrated herein is intended to represent onlycertain embodiments of the present invention, and is not intended toserve as limitations of alternative devices within the spirit and scopeof the invention.

1. A valve assembly, comprising: a rotary closure element defining anaxis of rotation and selectively movable between a fully open positionand a fully closed position; an impedance assembly mounted to andmovable with the rotary closure element, the impedance assembly defininga beveled inflow end and an outflow end, and comprising: a plurality offluid passageways extending from the inflow end to the outflow end; anda layer of wire mesh covering the inflow end; the impedance assembly andthe closure element collectively defining a flow opening which extendsfrom the inflow end to the outflow end; the fluid passageways and theflow opening being oriented relative to each other such that a portionof a flow through the valve assembly is directed into the fluidpassageways and a portion of the flow is directed through the flowopening when the closure element is in the fully open position.
 2. Thevalve assembly of claim 1 wherein the impedance assembly is configuredand oriented relative to the closure element such that the fluidpassageways are each downstream of the axis of rotation when the closureelement is in the fully open position.
 3. The valve assembly of claim 1wherein the impedance assembly is configured and oriented relative tothe closure element such that certain ones of the fluid passagewaysinclude portions which are upstream of the axis of rotation when theclosure element is in the fully open position.
 4. The valve assembly ofclaim 1 wherein: at least some of the fluid passageways are tortuous anddefine a series of turns which extend at generally right angles relativeto each other; and the tortuous fluid passageways of the impedanceassembly define differing numbers of turns.
 5. The valve assembly ofclaim 4 wherein the impedance assembly is mounted to the closure elementsuch that flow is applied initially to the tortuous passageways having agreater number of turns when the closure element is moved from the fullyclosed position toward the fully open position.
 6. The valve assembly ofclaim 1 wherein: the impedance assembly comprises a plurality ofimpedance plate assemblies secured to each other in a stackedarrangement along an axis which is generally parallel to the axis ofrotation; and each of the impedance plate assemblies includes aplurality of openings formed therein which collectively define the fluidpassageways when the impedance plate assemblies are stacked upon eachother.
 7. A valve assembly comprising: a rotary closure element definingan axis of rotation and selectively movable between a fully openposition and a fully closed position; and an impedance assembly mountedto and movable with the rotary closure element, the impedance assemblydefining an inflow end and an outflow end, and comprising: a pluralityof impedance plate assemblies secured to each other in a stackedarrangement along an axis which is generally parallel to the axis ofrotation, each of the impedance plate assemblies including a pluralityof openings formed therein which collectively define a plurality offluid passageways extending from the inflow end to the outflow end whenthe impedance plate assemblies are stacked upon each other, theimpedance plate assemblies and the closure element collectively defininga flow opening which extends from the inflow end to the outflow end,with each of the impedance plate assemblies comprising: a separatorplate; a first impedance plate having a plurality of slots and openingsformed therein; and a second impedance plate having a plurality of slotsand openings formed therein; the separator, first and second impedanceplates being stacked upon each other such that the second impedanceplate is disposed between the separator and first impedance plates, withthe slots and openings of the first and second impedance platescollectively defining the fluid passageways; the fluid passageways andthe flow opening being oriented relative to each other such that aportion of a flow through the valve assembly is directed into the fluidpassageways and a portion of the flow is directed through the flowopening when the closure element is in the fully open position.
 8. Thevalve assembly of claim 7 wherein: the closure element defines anarcuate outer surface; the impedance plate assemblies are configured ina manner wherein the outflow end of the impedance assembly is arcuatelycontoured; and the impedance assembly is mounted to the closure elementsuch that the arcuate outflow end of the impedance assembly issubstantially continuous with the outer surface of the closure element.9. The valve assembly of claim 8 wherein the impedance plate assembliesare configured in a manner wherein the inflow end of the impedanceassembly has a beveled configuration.
 10. A valve assembly comprising: arotary closure element defining an axis of rotation and selectivelymovable between a fully open position and a fully closed position; andan impedance assembly mounted to and movable with the rotary closureelement, the impedance assembly defining an inflow end and an outflowend, and comprising: a plurality of impedance plate assemblies securedto each other in a stacked arrangement along an axis which is generallyparallel to the axis of rotation, each of the impedance plate assembliesincluding a plurality of openings formed therein which collectivelydefine a plurality of fluid passageways extending from the inflow end tothe outflow end when the impedance plate assemblies are stacked uponeach other, the impedance plate assemblies and the closure elementcollectively defining a flow opening which extends from the inflow endto the outflow end; an upper cap; and a lower cap; the impedance plateassemblies being stacked between the upper and lower caps; the fluidpassageways and the flow opening being oriented relative to each othersuch that a portion of a flow through the valve assembly is directedinto the fluid passageways and a portion of the flow is directed throughthe flow opening when the closure element is in the fully open position.